The problem of severity in the classification of personality disorder.

The articles in this series are very valuable but have one omission that is very important in clinical practice; they do not address the question of severity. In this article I argue that the measure of severity, using what are described as hybrid models, is a critical component of practice and can be recorded easily using standard systems, both existing and planned. In arguing this case I will use an exemplar, the Personality Assessment Schedule (PAS), mainly because we have so much data from this instrument, but emphasize that other assessment procedures can be easily adapted to produce similar severity assessments.